21st Century Guidebook to Fungi, SECOND EDITION, by David Moore, Geoffrey D. Robson and Anthony P. J. Trinci

Table of Contents

1. Chapter 13: Ecosystem mycology: saprotrophs, and mutualisms between plants and fungi
2. Chapter 14: Fungi as pathogens of plants
   1. Fungal diseases and loss of world agricultural production
   2. A few examples of headline crop diseases
   3. The Rice Blast fungus Magnaporthe grisea (Ascomycota)
   4. Armillaria (Basidiomycota)
   5. Pathogens that produce haustoria (Ascomycota and Basidiomycota)
   6. Cercospora (Ascomycota)
   7. Ophiostoma (Ceratocystis) novo-ulmi (Dutch Elm disease or DED) (Ascomycota)
   8. Black stem rust (Puccinia graminis f. sp. tritici) threatens global wheat harvest
   9. Plant disease basics: the disease triangle
   10. Necrotrophic and biotrophic pathogens of plants
   11. The effects of pathogens on their hosts
   12. How pathogens attack plants
   13. Host penetration through stomatal openings
   14. Direct penetration of the host cell wall
   15. Enzymatic penetration of the host
   16. Pre-formed and induced defence mechanisms in plants
   17. Genetic variation in pathogens and their hosts: co-evolution of disease systems
   18. Chapter 14 References and further reading
   19. Buy a PDF of Chapter 14
3. Chapter 15: Fungi as symbionts and predators of animals

14.6 Cercospora (Ascomycota)

Many species of this genus cause plant diseases, mostly of the ‘leaf spot’ variety. Leaf spots are rounded blemishes occurring on the leaves of the infected plants; a typical spot has a defined edge with a darker border and a central zone varying from yellow to brown. Numerous spots can merge together and the larger areas can be called blights or blotch diseases.

Cercospora is not the only cause of leaf spot diseases but it causes disease on: alfalfa, asparagus, banana, brassicas, Cannabis, carrot, celery, cereals, coffee, cucumber, figs, geraniums, grapes, grasses, hazel, hops, lentil, lettuce, mango, millet, orchids, papaya, peanut, pear, peas, peppers, potato, roses, sorghum, soybean, spinach, strawberry, sugar beet, sugarcane (the spots merge into stripes; so the disease is called ‘black stripe’), sycamore, tobacco, watermelon, and many wild plants and ornamentals.

Cercospora beticola is the most destructive leaf disease of sugar beet worldwide; the disease reduces yield and quality of sugarbeet and the need to use fungicide to control leaf spot disease adds significantly to the cost of production. C. beticola overwinters as stromata in infected crop residues and spores produced on these are the prime source of infection of the leaves of the next season’s crop (Khan et al., 2008).

Disease control strategies rely on a combination of fungicide applications (alternating and combining fungicides differing in modes of action to avoid resistance development in the fungus), growing resistant cultivars, and appropriate crop rotation (to avoid the overwintering stromata).

Improvement of these integrated pest management systems is the main hope, now, for more effective and environmentally sound disease control. Plant varieties with greater genetic resistance is central to this, but pathogen-resistant strains often have lower yields in the absence of the disease, which is unacceptable in commercial practice. Promisingly, yield performance of recently isolated sugar beet varieties with resistance to Cercospora beticola have equalled yields of susceptible varieties and should allow reduced fungicide to be use in integrated pest management programmes (Skaracis et al., 2010; Vogel et al., 2018).

Resources Box 14.1 Where to find more information about crop diseases, crop losses, plant pathogens and food and agriculture statistics We have a page giving references to scientific papers and hyperlinks to online resources. CLICK HERE to open the page in a new window

Updated July, 2019